1. Project

2. Project
FINAL PROJECT DELIVERABLES 1) PROJECT REPORT: - Project statement (introduction) 2 pages Explain what are you designing/analyzing and why is that important On the second page clearly identify (bullet list) project outcomes - Building description (geometry) 1-3 pages Schematics that focus on your system(s) Identify all assumptions and simplifications you introduced - Methodology 1-3 pages Describe methodology (equations, schematics, …) Provide a list of assumptions used in your methodology - Results 3-5 pages Formatted results with comments Tables, Charts, Diagrams, … Analysis and Results discussion - Summary page Summary of most important results

3. Project Grading criteria: 1) Approach and solution quality: 60%
1) Approach and solution quality: 60%
- Methodology %
- Accuracy 20%
Result analysis 20%
2) Deliverables: %
- Final report 40%
- clarity
- completeness
- steed assumptions and limitations
- quality of graphs, tables schematics,….

4. Objectives Learn about 1) DOAS - Principle of operation - Design
- Advantages and disadvantages
2) Control for HVAC systems
- Economizers (Psychrometrics) and control
- Heat recovery systems (Psychrometrics)

5. www.doas.psu.edu DOAS with multi-split systems
Fresh air?

6. DOAS fresh air configurations

7. DOAS fresh air configurations

8. Issues Related to DOAS Split of sensible and latent load
Selection of hydronic system
Winter vs. summer operation
Winter operation with DX systems (heat pump)

9. Economizer Economizer (fresh air volume flow rate control)
Controlled device is damper
- Damper for the air
- Valve for the CC
fresh
air
damper
mixing
recirc.
air
T & RH sensors

10. Economizer – cooling regime
How to control the fresh air volume flow rate?
If TOA < Tset-point → Supply more fresh air than the minimum required
The question is how much?
Open the damper for the fresh air
and compare the Troom with the Tset-point .
Open till you get the Troom = Tset-point
If you have 100% fresh air and your
still need cooling use cooling coil.
What are the priorities:
- Control the dampers and then the cooling coils or
- Control the valves of cooling coil and then the dampers ?
Defend by SEQUENCE OF OERATION
the set of operation which HVAC designer provides to the automatic control engineer
% fresh air
100%
Minimum for
ventilation

11. Economizer – cooling regime
Example of SEQUENCE OF OERATIONS:
If TOA < Tset-point open the fresh air damper the maximum position
Then, if Tindoor air < Tset-point start closing the cooling coil valve
If cooling coil valve is closed and T indoor air < Tset-point start closing the damper
till you get T indoor air = T set-point
Other variations are possible

12. Sequence of operation for the humidity control system design
Adiabatic
humidifier CC HC SA OA
mixing RA
Define the sequence of operation for:
WINTER operation and:
- case when humidity is not controlled
- case when humidity is precisely controlled

13. Sensible and Enthalpy and Desiccant wheels

14. Sensible and Enthalpy Wheels

15. Desiccant wheel
Figure 3 – A desiccant-based cooling system combined with regenerative heat exchanger, vapor compression cooling, and evaporative humidifier (hybrid system).